1. Field of the Invention
This invention relates to a formulation for decontaminating a variety of toxic agents.
2. Background of the Related Art
Over many years, various highly toxic chemical and biological warfare agents have been developed and stockpiled by several nations. These weapons are very efficient in causing multiple casualties and cannot easily be detected, making their production and eventual deployment difficult to monitor. In addition, these weapons cost relatively little to produce and are easy to manufacture. In view of the hazards associated with these agents, it is essential to have formulations which can rapidly and efficiently decontaminate surfaces which have been exposed to these chemical and biological warfare agents.
An important aspect of any containment strategy is to be able to neutralize the threat using chemical decontamination methods. Most chemical warfare agents (CWA""s) and biological warfare agents (BWA""s) can be destroyed or rendered harmless by suitable chemical treatments. Unfortunately, existing chemical treatments for neutralization of biological and chemical agents have significant drawbacks. A xe2x80x9cuniversalxe2x80x9d formulation that can decontaminate all biological and chemical threats is not available. Existing decontamination solutions are only effective against a certain class of agents. In order to be effective, emergency response personnel would need several types of decontaminants available on-hand. Use of existing decontaminants under inappropriate conditions can result in the formation of dangerous by-products. For example, a dilute bleach solution is very effective at destroying anthrax spores, but an extremely toxic by-product is formed if used to destroy VX. Furthermore, some chemicals, such as sodium hydroxide dissolved in organic solvents are unsuitable for use in certain conditions because they corrode, etch or erode materials.
Today, many different types of CWA""s and BWA""s are known. The CWA""s fall into three main classes: sulfer mustards (HD), nitrogen mustards (HN3), and organophosphorous nerve agents (acetylcholinesterase inhibitors) of the G (GA, GB, GD, GE, GF) and V (VX, VE, VG, VM) type. BWA""s can be classified into at least five categories: viruses, bacteria, rickettsia, biological toxins, and genetically engineered agents.
Most decontamination processes include some form of hydrolysis. Hydrolysis of CWA""s creates intermediates or oxidation by-products of organophosphorous compounds that are sometimes more toxic than the agent itself. While hydrolysis may be acceptable for many organophosphorous compounds, it is not universally effective against all of these compounds and great care must be taken to first identify then treat the agent under the proper hydrolyzing conditions.
The oxidation of neutral organo-phosphorous esters (OPEs) usually involves atoms other than phosphorus. In compounds containing sulfur, oxidation generally occurs at the sulfur atom In unprotected nitrogen moieties, oxidation at nitrogen will occur and may result in increased inhibition of acetylcholine esterase. From a toxicological standpoint, random oxidation of organophosphorous compounds at critical sites could result in the production of better esterase inhibitors.
These considerations highlight the need for a system capable of decontaminating a broad range of chemical and biological agents without producing toxic by-products. In addition, there is a need for a decontamination system that is compatible with most common materials, easy to dispense and environmentally safe.
The present invention provides for a formulation for decontaminating toxic agents such as chemical and biological warfare agents and pesticides. The formulation comprises a sorbent containing HSO5xe2x88x92 ions, an oxidant, and an activator dispersed in the oxidant for activating the oxidant. Preferably, the compound containing HSO5xe2x88x92 ions is selected from potassium monopersulfate, sodium monopersulfate, ammonium monopersulfate, HSO5xe2x88x92 salts of other alkali metals, and HSO5xe2x88x92 salts of alkaline earth metals, most preferably having, formula 2KHSO5.KHSO4.K2SO4, which is commercially available as OXONE.
The oxidant can be selected from perborates, persulfates, organic peroxides, alkali metal peroxides, alkali metal superoxides, and alkaline earth metal peroxides, preferably hydrogen peroxide. There are a number of known activators for peroxide oxidation reactions. Some useful activators include iron salts, as well as the salts of copper, titanium, chromium, vanadium, zinc, cobalt, and nickel. Finely divided metals capable of being readily oxidized to form metal cations are considered to be within the scope of this invention. Preferably, the activator is in the form of ferrous ions. In addition, phosphate ions may also be used in the formulation to control the temperature of the reaction.
The sorbent material may be selected from silicon dioxide, silica gel, silicon oxyhydroxides, aluminum oxide, alumina gel, aluminum oxyhydroxides, aluminates, other metal oxides, other metal oxyhydroxides, clay minerals and mixtures thereof, preferably, fumed silica. The ideal sorbent is inert and has a high surface area and capacity for absorbing or adsorbing the contaminants.
The HSO5xe2x88x92 ion concentration can range from about 0.05M to about 0.5M, preferably from about 0.1M to about 0.3M. The oxidant concentration can range from about 0.5M to about 5M, preferably from about 0.5Mxe2x80x94 to about 1.5M. The activator concentration can range from about 0.05M to about 0.5M, preferably from about 0.1M to about 0.3M. The final sorbent material concentration may be from about 3% to about 20% by weight, preferably from about 5% to about 15% by weight.
A system for decontaminating toxic agents is also provided. The system comprises an HSO5xe2x88x92 ion, an oxidant capable of forming free hydroxyl radicals, a metal catalyst or activator dispersed within the oxidant, and a sorbent material, wherein the HSO5xe2x88x92 ions, the oxidant and the metal catalyst are dispersed within the sorbent material. Preferably, a dispenser is provided with a first compartment for holding the HSO5xe2x88x92 ions and the oxidant dispersed in the sorbent material and a second compartment for holding the metal catalyst or activator dispersed in the sorbent material. The dispenser may also have a nozzle with a mixer for mixing the HSO5xe2x88x92 ions and oxidant with the metal catalyst or activator. The sorbent compounds containing HSO5xe2x88x92 ions, the oxidant, and the metal catalyst are described above. Preferably, the ratio of oxidant to HSO5xe2x88x92 ion is 90:10.
In another embodiment of the present invention, there is provided a method for decontaminating a toxic agent disposed on a surface. The method includes reacting the toxic agent with a sufficient amount of a solution containing an HSO5xe2x88x92 ion, an oxidant, and a metal catalyst or activator for activating the oxidant for a sufficient time and under conditions sufficient to produce a reaction product having less toxicity than the toxic agent. Preferably, the reaction product produced is non-toxic. The non-corrosive compound may include a sorbent gel with the HSO5xe2x88x92 ion, the oxidant, and the metal catalyst or activator dispersed therein. Preferably, the toxic agent is absorbed into the sorbent gel, which blocks any contact between the toxic agent and the surrounding atmosphere. Once the decontamination reaction has taken place, the compound and reaction product can be easily removed from the surface without damaging the surface. A variety of toxic agents can be decontaminated using this method, including but not limited to mustard gas, G-agents, V-agents, spores and mixtures thereof.
The compound containing HSO5xe2x88x92 ions is preferably selected from potassium monopersulfate, sodium monopersulfate, ammonium monopersulfate, HSO5xe2x88x92 salts of other alkali metals, and HSO5xe2x88x92, salts of alkaline earth metals, most preferably having the formula 2KHSO5, KHSO4, K2SO4. The oxidant can be selected from perborates, persulfates, organic peroxides, alkali metal peroxides, alkali metal superoxides, and alkaline earth metal peroxides, the preferred metal catalyst or activator is ferrous cations.
In yet another embodiment, there is provided a method for preparing a decontamination product. The method includes mixing a compound containing an HSO5xe2x88x92 ion and an oxidant capable of forming free hydroxyl radicals to form an oxidation component and providing a metal catalyst or activator to bring about the formation of hydroxyl radicals in a separate container. Preferably, the oxidation component is mixed with a sorbent material and the metal catalyst or activator is mixed with a sorbent material. A dispensing element may be provided that mixes the oxidation component with the metal catalyst on demand for easy application of the decontamination product.